Irrigation controllers are commonly known in the prior art. They are electromechanical devices that control water delivery to a plurality of zones through the programmed opening and closing of water control valves, such as solenoid valves. For example, a residential landscape may be divided into eight separate watering zones. Some of the zones encompass turf requiring relatively more water delivered through sprayers. Some of the zones encompass bushes and trees requiring relatively less water delivered through bubblers and drip emitters. Homeowners or landscapers program the irrigation controller to deliver different amounts of water to these different zones by varying the amount of time the water control valves remain open in the course of a given irrigation cycle. For example, the valve covering Zone 1, a turf zone, may be programmed to be open five days per week (“watering days”), three times per day at specific times of the day (“start time”) for ten minutes (“run-time duration”); the valve covering Zone 2, a bush and tree zone, may be programmed to be open only three days per week, three times per day immediately following the cycles of Zone 1, but with run-time durations of only five minutes; and so on and so forth.
A limitation of such existing irrigation controllers is that they must be manually reprogrammed to respond to seasonal changes, as well as to watering restrictions mandated by local water authorities (“mandated watering restrictions”). Ten minutes of water, three times per day may be appropriate for a turf zone in summer, but excessive for winter. Moreover, in summer, the irrigation controller may be programmed to water on any day of the week, but in winter, mandated watering restrictions may limit “allowed watering days” to just one day per week, with six days a week mandated as “mandated no watering days.” To effect the changes needed to adjust for the seasons and mandated watering restrictions, homeowners and landscapers must manually reprogram the controller.
Because the foregoing changes are few in number—typically four times per year corresponding to the four seasons—and because conventional irrigation controllers are relatively easy to reprogram, implementing the required seasonal changes and mandated watering restrictions should be an acceptable burden. However, even if homeowners and landscapers faithfully reprogram their irrigation controllers these four times per year, this would still result in a substantial amount of water waste. Moreover, local water authorities find that their water conservation programs are far less effective than they should be due to the failure of homeowners and landscapers to comply with mandated watering restrictions, because even the few and simple steps needed to comply with them are too difficult for many homeowners and landscapers, or they simply do not implement them.
The water waste inherent in four-times-per-year reprogramming of conventional irrigation controllers is caused by the fact that the water demand of plants changes far more frequently than just four times per year. The water demand of plants is dictated by the rate at which plants lose moisture to evaporation, and the rate at which they are capable of replacing it (“evapotranspiration”). Evapotranspiration is influenced by many factors, including temperature, humidity, soil moisture, soil type, sun exposure, wind, type/amount of mulch, and, of course, plant type.
Some factors, such as plant type and sun exposure, are taken into account through the regular programming of a conventional irrigation controller. For example, a homeowner knows he has trees and shrubs, not turf, in Zone 2 of his yard, and that this portion of the yard is shaded from the sun. He takes this into account by watering Zone 2 with bubblers and drip emitters, rather than the sprayers used on turf zones. He also takes it into account by programming his conventional irrigation controller with start times and run-time durations that make sense for this plant type and for shade conditions (as well as soil type and other factors).
However, the homeowner cannot take evapotranspiration factors into account in this way. For example, temperature, humidity and wind fluctuate constantly, changing the water demand of plants constantly—and far more often than four times per year. Reprogramming an irrigation controller four times per year takes into account a range of these fluctuations. For example, in summer, temperatures in the Las Vegas Valley typically range between 80° F. and 115° F., versus winter when they may range between 35° F. and 65° F. The fact is, however, that these ranges are very broad. For example, an irrigation controller programmed to deliver water in accordance with the average anticipated temperature in the middle of the range may result in plant loss during hot, dry spells in midsummer, yet may deliver more water than is necessary at the beginning and end of the summer season. Thus, the current situation is detrimental to both homeowners (less than optimal water delivery) and the water authority (extra water use early and late in season).
With regard to mandated watering restrictions, some non-compliance is due to unwillingness of homeowners and landscapers to obey them. However, most non-compliance, according to local water authorities, is due to indifference or ignorance of the mandated watering days, despite local water authorities' best efforts to publicize them, or is due to confusion over when and where they apply. For example, different sections of a local water authority's jurisdiction may be assigned a watering group, such as “A” or “B.” Homeowners in “A” may be assigned the allowed watering days Monday, Wednesday and Friday. Homeowners in “B” may be assigned the allowed watering days Tuesday, Thursday and Saturday. Thus, a homeowner must know whether he is in assigned watering group “A” or “B,” and must additionally know the allowed watering days for that watering group—all of which changes four times per year. As simple as this may seem, it is apparently too much for a substantial percentage of homeowners and, to the extent homeowners rely on them, landscapers.
Industry has responded to the foregoing problems by creating what are known as “smart controllers.” Following are examples of different approaches taken by smart controller developers.
One approach has been to make irrigation more scientific by benefiting from academic research on evapotranspiration. U.S. Pat. No. 5,208,855 issued to Marian discloses a smart controller outfitted with a receiver to pick up evapotranspiration data broadcast by weather stations and agricultural extensions. Such broadcasts consist of daily information for various localities about environmental factors such as temperature, humidity and wind. These data have been processed to determine their effect on evapotranspiration and, thus, water need for a reference crop, generally turf (determining what is known as reference evapotranspiration or “ETo”). Upon setting up the Marian smart controller, the user inputs locality and information about the type of plants he is irrigating, so that the smart controller may automatically pick up the broadcast ETo information corresponding to the user's locality, and calculate the water need of the user's plant matter as a percentage of ETo (based upon crop coefficients, which are published analyses of the evapotranspiration water needs of plant types as a percentage of the evapotranspiration water needs of the reference crop). Unfortunately, Marian's smart controller has numerous drawbacks for the average homeowner: (1) its emphasis on crop coefficients is suited to agriculture, not average homeowners, (2) the need for a receiver and relatively complicated data entry screen contribute to cost and complexity, and (3) the need for the homeowner to reset his irrigation controller seasonally is not removed. In the case of agriculture, these drawbacks are less important, because farmers are willing to, and do devote great attention to irrigation systems. Average homeowners do not, and a disruption to irrigation, for example, could subsist for days before a homeowner even noticed it. Additionally, Marian's smart controller does not facilitate the water authority's goal of increased compliance with mandatory watering restrictions.
U.S. Pat. No. 6,453,216 issued to McCabe et al. and U.S. Pat. No. 6,892,113 issued to Addink et al. disclose devices using historical evapotranspiration data as the means to determine a watering budget (McCabe et al.) or as part of the means to do so (Addink et al.). For example, historical evapotranspiration data may consist of an average of the evapotranspiration data for the same date over a multiyear period, e.g., December 1, for a specific location, e.g., Amarillo, Tex., for the three years 2000, 2001 and 2002. The advantage of using historical evapotranspiration data is that they free the user from needing to obtain current data, for example, by broadcast transmission, and entering current data into the smart controller. Instead, the historical data can be preloaded into the smart controller, enabling the smart controller to deliver water in accordance with the average historical evapotranspiration for that date and location. U.S. Pat. No. 6,314,340 issued to Mecham et al. discloses a device that measures high and low temperatures for the day, and then uses a specific formula, namely, the Hargreaves formula, to determine an appropriate watering budget. However, none of these patents address the problems of lack of compliance with mandated watering restrictions or with the troublesome requirement for the homeowner to reset the irrigation schedule of his irrigation controller each season to meet seasonal watering needs and/or seasonal mandated watering restrictions.
Another approach has been to create smart controllers capable of tracking one or more of the environmental factors affecting evapotranspiration rate, and increasing or decreasing water output in accordance with them. For example, U.S. Pat. No. 4,684,920 issued to Reiter and U.S. Pat. No. 4,922,433 issued to Mark focus on soil moisture. Using sensors placed in the ground throughout the area to be irrigated, these smart controllers benefit from real-time soil moisture readings in order to provide the right amount of irrigation. However, while these devices may be suitable for agricultural or commercial use (e.g., golf courses and shopping centers), they are not suitable for average homeowners, because the deployment and maintenance of soil sensors require too much effort and expense relative to homeowners' modest landscaping needs.
U.S. Pat. No. 6,892,114 issued to Addink et al., and U.S. Pat. No. 7,165,730 issued to Clark disclose smart controllers capable of measuring one or more environmental factors for the purpose of modifying the irrigation schedule of a conventional controller. However, both devices disclose suboptimal design, since they are not in series between an existing controller and the irrigation valves, but communicate only with the existing controller to modify an irrigation cycle, as discussed in greater detail below. U.S. Pat. No. 7,266,428 issued to Alexanian focuses solely on temperature as the predominant environmental factor affecting evaporation rate, and uses a non-standard evapotranspiration formula based solely on temperature to create water budgets.
U.S. Pat. No. 5,839,660 issued to Morgenstern et al. focuses primarily on precipitation and wind, disclosing a smart controller that measures these environmental factors and cuts off irrigation if either one exceeds a set value.
However, the smart controllers using environmental factors presented in these patents do not increase compliance with mandated watering restrictions nor decrease the work for the homeowner in resetting the irrigation controller at least seasonally.
Yet another approach has been to provide smart controllers giving users greater control over their irrigation systems. For example, U.S. Pat. No. 7,010,396 issued to Ware et al. covers an irrigation controller with an embedded Web server enabling the user to interact remotely and, hence, more frequently and conveniently with the controller. However, for the average homeowner, what is needed is not more involvement with the irrigation controller, but greater irrigation efficiency without more involvement.
Further, when adjusting the watering run-time duration or cutting off the irrigation, smart controllers of the prior art do not take into consideration the number of mandated no-watering days blocked out and the additional increased reduction in water delivery. For instance, in some regions in winter, there is only one allowed watering day per week, with six days of the seven mandated as no-watering days. If the irrigation is cut off on the one allowed watering day (such as due to an environmental factor), no irrigation will be given for two weeks. Similarly, as described in U.S. Patent Publication No. 2010/0030476 by Woytowitz et al., on the one allowed watering day, the watering run-time duration may be reduced by a relatively large percentage based on environmental factors through a seasonal adjust feature based on historical evapotranspiration rates, without accounting for the additional reduction forced by the six mandated no-watering days.
Unfortunately, no prior art device has effectively solved the problem of making irrigation efficiency more affordable and less burdensome for the average homeowner, while providing a simple means to implement local mandated watering restrictions, and thus promote the water-saving goals of the local water authority by increasing compliance. Smart controllers' complexity and expense, as well as their suboptimal design and methodology, have prevented them from penetrating this market that is crucial not only from a profit standpoint, but from a water and energy conservation standpoint. (For example, pumping water to the Las Vegas Valley is the region's single greatest use of energy.)